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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 598 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 380 + 563? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 223 + 592? (a) 600 (b) 800 (c) 1000
  3. 3.Best estimate of 655 + 320? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 153 + 351? (a) 600 (b) 800 (c) 400
  5. 5.Best estimate of 629 + 805? (a) 1400 (b) 1200 (c) 1600
  6. 6.Best estimate of 487 + 634? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 491 + 405? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 83 × 91? (a) 72000 (b) 7200 (c) 720
  9. 9.Best estimate of 97 × 18? (a) 2000 (b) 20000 (c) 200
  10. 10.Best estimate of 584 + 265? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 281 + 425? (a) 900 (b) 700 (c) 500
  12. 12.Best estimate of 26 × 56? (a) 1800 (b) 180 (c) 18000
  13. 13.Best estimate of 31 × 77? (a) 24000 (b) 240 (c) 2400
  14. 14.Best estimate of 614 + 184? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 51 × 56? (a) 30000 (b) 3000 (c) 300
  16. 16.Best estimate of 570 + 545? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 504 + 307? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 53 × 81? (a) 40000 (b) 400 (c) 4000
  19. 19.Best estimate of 215 + 848? (a) 800 (b) 1200 (c) 1000
  20. 20.Best estimate of 13 × 14? (a) 10 (b) 100 (c) 1000
  21. 21.Best estimate of 78 × 13? (a) 80 (b) 8000 (c) 800
  22. 22.Best estimate of 31 × 26? (a) 900 (b) 9000 (c) 90
  23. 23.Best estimate of 14 × 56? (a) 600 (b) 6000 (c) 60
  24. 24.Best estimate of 70 × 92? (a) 6300 (b) 63000 (c) 630
  25. 25.Best estimate of 187 + 583? (a) 600 (b) 800 (c) 1000
  26. 26.Best estimate of 283 + 593? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 755 + 259? (a) 1100 (b) 900 (c) 1300
  28. 28.Best estimate of 53 × 66? (a) 350 (b) 3500 (c) 35000
  29. 29.Best estimate of 791 + 475? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 260 + 369? (a) 700 (b) 900 (c) 500
  31. 31.Best estimate of 13 × 58? (a) 6000 (b) 60 (c) 600
  32. 32.Best estimate of 320 + 661? (a) 800 (b) 1000 (c) 1200
  33. 33.Best estimate of 389 + 275? (a) 700 (b) 900 (c) 500
  34. 34.Best estimate of 758 + 212? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 272 + 758? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 689 + 239? (a) 700 (b) 1100 (c) 900
  37. 37.Best estimate of 53 × 48? (a) 25000 (b) 2500 (c) 250
  38. 38.Best estimate of 48 × 53? (a) 2500 (b) 250 (c) 25000
  39. 39.Best estimate of 815 + 599? (a) 1600 (b) 1200 (c) 1400
  40. 40.Best estimate of 627 + 726? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 1000
  2. 800
  3. 1000
  4. 600
  5. 1400
  6. 1100
  7. 900
  8. 7200
  9. 2000
  10. 900
  11. 700
  12. 1800
  13. 2400
  14. 800
  15. 3000
  16. 1100
  17. 800
  18. 4000
  19. 1000
  20. 100
  21. 800
  22. 900
  23. 600
  24. 6300
  25. 800
  26. 900
  27. 1100
  28. 3500
  29. 1300
  30. 700
  31. 600
  32. 1000
  33. 700
  34. 1000
  35. 1100
  36. 900
  37. 2500
  38. 2500
  39. 1400
  40. 1300

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